Recently, glasses having a variety of color tones have been proposed as window glasses of vehicles. Among them, a glass with a relatively low visible light transmittance preferably is used for a rear window glass of a vehicle in view of privacy protection. Such kinds of glasses include the following.
JP2001-19471A discloses a dark green colored glass including 0.7 to 1.6 wt % of Fe2O3 (total iron), 0.10 to 0.23 wt % of FeO, 0.010 to 0.100 wt 0% of CoO, 0.010 to 0.100 wt % of NiO, and 0 to 0.0008 wt % of Se.
JP2003-522706T discloses a gray glass composition with a total light transmission of at least 15% when measured at a thickness of 4.85 mm, including 0.25 to 0.65 wt % of Fe2O3, 150 to 250 wt. ppm of CoO, and less than 5 wt. ppm of Se.
The present applicant discloses, in JP10 (1998)-114540A, an ultraviolet/infrared absorbent low transmittance glass with an almost neutral color such as a bluish green or deep green color, including 1.2 to 2.2 wt % of total iron oxide (T-Fe2O3) expressed in terms of Fe2O3, 0.001 to 0.03 wt % of CoO, 0 to 0.0008 wt % of Se, and 0 to 0.2 wt % of NiO.
All of the well-known glasses having a grayish color tone include high concentrations of selenium. Selenium not only has a serious impact on the environment, but it is a substance that is very easily vaporized. Therefore, it is preferred to avoid the use of selenium.
A glass disclosed by the present applicant in JP10 (1998)-114540A does not have a grayish color tone but a bluish green or deep green color, although it includes only a small amount of selenium.
A glass disclosed in JP2001-19471A has only a dark green color, although it also includes only a small amount of selenium.
Furthermore, a glass disclosed in JP2003-522706T includes only a small amount of selenium and has a gray color tone. However, this glass composition has a problem that its ultraviolet transmittance is too high due to its relatively low content of Fe2O3.